1. Technical Field
The present invention relates to a semiconductor memory device and a method of precharging global input/output lines thereof, and more particularly, to a semiconductor memory device and a method of precharging global input/output lines thereof for reducing the power consumed during a precharge operation of global input/output lines.
2. Discussion of the Related Art
A typical semiconductor memory device writes or reads data to or from memory cells contained within internal memory banks using layered I/O lines with a need to precharge the layered I/O lines before or after write or read operations.
As the storage capacity of the semiconductor memory device increases, the semiconductor memory device is provided with more memory banks, and the length of global I/O lines running over the increased number of memory banks is increased accordingly.
As the number and the size of precharge drivers for precharging the global I/O lines is also increased, the power consumed for precharge operations is also increased.
In a conventional semiconductor memory device, the global I/O lines are divided into upper global I/O lines running over upper memory banks and lower global I/O lines running over lower memory banks. The upper and lower global I/O lines are connected or disconnected by a switching portion.
For example, in the case that the upper memory banks are selected, the switching portion connects the upper global I/O lines and the lower global I/O lines, so that data is input or output through the upper and lower global I/O lines. In the case that the lower memory banks are selected, the switching portion disconnects the upper global I/O lines and the lower global I/O lines, so that data is input or output only through the lower global I/O lines.
As described above, the semiconductor memory device does not use all the global I/O lines in write or read operations. That is, when the lower memory bank is selected and data is input or output only through the lower global I/O lines, the upper global I/O lines are not used, an existing precharge voltage Vdd is maintained and the upper global I/O lines do not require a precharge operation.
The conventional semiconductor memory device receives bank selection signals from the outside and selects a specific memory bank among a plurality of memory banks.
Therefore, a need exists for a semiconductor memory device which detects the region of the global I/O lines through which data is input or output, using the bank selection signal, and actuates only a precharge driver corresponding to the region of the detected global I/O lines performing a precharge operation, thereby reducing the power consumption during precharge operations.